1. Field of the Invention
The present invention relates to a method for fabricating a liquid crystal display panel, more particularly, to a method for fabricating a polymer stabilized alignment liquid crystal display (PSA-LCD) panel.
2. Description of Related Art
With the continuous advancement of the liquid crystal display (LCD) device towards to the large-size display standard, the market is gravitating towards LCDs having characteristics such as high contrast ratio, rapid response, and wide viewing angle. Therefore, the wide viewing angle techniques of the liquid crystal display panel are continuously developed in order to overcome the viewing angle problem of the large-size display device. Currently, multi-domain vertical alignment (MVA) LCD panels and polymer stabilized alignment (PSA) LCD panels are conventional wide viewing-angle technologies.
Take the method for fabricating the PSA-LCD panels as an example, the fabricating method thereof is complicated. FIG. 3 schematically illustrates a flow chart of the method for fabricating a conventional PSA-LCD panel. Referring to FIG. 3, the method for fabricating the conventional PSA-LCD panel includes formation of polyimide (PI) alignment films, sealant dispensing, liquid crystal dispensing, vacuum assembly of substrates, sealant curing, UV exposure, cells cutting, cells grinding, polarizer attaching, and so on. It is noted that, during fabrication of the PSA-LCD panels, the liquid crystal layer having monomer doped therein is used, a predetermined bias is applied to the liquid crystal layer, and the liquid crystal layer is irradiated by UV light. At this time, the monomer doped in the liquid crystal layer polymerizes to form polymer layers at two opposite sides of the liquid crystal layer such that the liquid crystal molecules are aligned by the polymer layers. Since the fabrication of PI alignment films includes pre-cleaning, PI coating, pre-baking and post-baking, the complexity of the PSA-LCD panels is increased due to the fabrication of PI alignment films.
Currently, some PI-less technologies have been proposed by prior arts so as to reduce the complexity of the PSA-LCD panels. Specifically, the above-mentioned PI-less technologies are usually applied to liquid crystal cells having alignment protrusions. The alignment protrusions make the liquid crystal molecules pre-tilt. However, the PI-less technologies only vertically aligned the liquid crystal molecules. Since only parts of the liquid crystal molecules distributed around the alignment protrusions are pre-tilted, response of the liquid crystal layer is slow. In addition, light leakage often occurs at the regions corresponding to the alignment protrusions, and the contrast ratio of the PSA-LCD panels decrease accordingly.
How to improve the contrast ratio and enhance response without increasing complexity of fabricating process of the PSA-LCD panels is an important issue to be solved.